The previous chapter described different methods for outputting a finished production to a variety of media. In many cases, the production then undergoes a technical quality control (or QC) check to ensure that it meets the required technical standard for broadcast or theatrical release. The QC process is necessary because of the many links in the production chain. Material is supplied from multiple sources and run through many separate processes, and a number of different companies may have handled it. The QC process is essential in ensuring that an acceptable level of quality is maintained, regardless of the processes used until this point.